The 'commoner act' Princess Margaret was once caught doing

Prince Harry may be viewed as the 'rogue' of the Royal Family these days, but not so long ago that rule-breaking reputation was embodied by Princess Margaret.

In her life, the younger sister of Queen Elizabeth II was renowned for her charisma (and sharp tongue) and her glamorous lifestyle, making her both a breath of fresh air and a source of drama for the stuffy institution she was born into.

Margaret's antics are legendary, thanks to anecdotes, media coverage, and the recent portrayal of her in The Crown. Yet very few royal watchers can say they've witnessed her in action.

LISTEN: The new episode of The Windsors delves into the life of the late Princess Margaret. (Post continues.)

Victoria Arbiter is one of the small group who can.

In 'The Rebel Princess', the latest episode of The Windsors podcast, 9Honey's royal commentator reflects on her own highly amusing encounter with Princess Margaret.

At the time, Arbiter—whose father Dickie Arbiter is Her Majesty's former press spokesman—was fresh out of school and working as a VIP host at a theatre in the UK.

"We were told Princess Margaret was coming that night and I was going to be looking after her," she recalls, adding that her daughter Lady Sarah would also be in attendance.

The late Princess Margaret pictured in 1960, with her then-fiance Antony Armstrong Jones. (AP/AAP)

Arbiter and her fellow staff members spent the day ensuring everything would be perfect for the royal arrival—including an ample supply of Grouse scotch, Margaret's drink of choice at the time.

"She loved it. We had bottles of the stuff just in case we didn’t have enough," she continues.

"She had several of those famous Grouse scotches before we went into the theatre, and it was my job to show her to her seat. So I was walking up the stairs, leading her through, and I turned around and Princess Margaret was gone.

"I thought, 'Oh God, I’m going to be fired. I’ve lost Princess Margaret. Where could she possibly have gone?'"

WATCH: Victoria Arbiter walks us through the family relationships within the British monarchy. (Post continues.)

Mildly panicked, Arbiter turned to the front row of the theatre, where Princess Margaret would be sitting during the performance.

Put it this way: what she saw was not behaviour one would necessarily expect of the Queen's sister.

"This was Princess Margaret, she was her own woman and she was going to do what worked for her. If that meant a gin and a cigarette for breakfast, so be it," Arbiter adds.

Listen to The Windsors to find out how, exactly, the late 'rebel princess' had taken matters into her own hands during that night at the theatre.